The present invention relates to continuous ink jet printing and, more particularly, to placement of an eyelid seal relative to a catcher pan by means of various flexures.
Ink jet printing systems are known in which a print head defines one or more rows of orifices which receive an electrically conductive recording fluid from a pressurized fluid supply manifold and eject the fluid in rows of parallel streams. Printers using such print heads accomplish graphic reproduction by selectively charging and deflecting the drops in each of the streams and depositing at least some of the drops on a print receiving medium, while others of the drops strike a drop catcher device.
When the ink jet print head is not in operation, means must be provided to seal the print head so that ink does not dry in the catcher face area, or weep from the jets and soil the apparatus or adjacent work surfaces. In continuous ink jet printing systems, the eyelid is a moveable seal which diverts ink on startup into the catcher, thereby recycling the ink while containing it within the printhead. The seal is formed against the lip of the metal catch plate, which is typically about 0.025 inches thick. The eyelid opens about 0.04 inches while the printer is printing, allowing the ink drops to pass onto the print media.
As a continuous ink jet printer starts up in preparation for printing, it is necessary to divert the partially formed jets and blobs of ink into a catcher and evacuate ink from the vicinity of the charge leads. The eyelid is a moveable seal which diverts the ink and seals on its lower edge against the catcher pan. A small gap (xe2x80x9c0.020xe2x80x9d) exists between the face of the seal and the radius of the catcher. If this gap is too small, the flow of ink into the catcher throat can be restricted. This can result in a failure at printhead startup as ink overflows the eyelid as the pressure transitions from low to high. A large gap between the eyelid and catcher radius will create a recirculation zone in the throat of the catcher, which also causes ink to flow over the eyelid. Both situations can lead to startup failures. Similarly, an eyelid seal which is too high will obstruct the catcher throat, also leading to startup failures. If the eyelid seal is located too low, the seal between the eyelid and the catcher pan may leak.
One way of achieving an exact placement of the eyelid seal to the catcher pan is through tightening the part tolerances. The eyelid and catcher components are precisely fabricated, creating a precise assembly. However, this method leads to increased part cost and is difficult to implement as the part count increases.
It is seen then that there exists a need for an improved eyelid positioning technique which can be used to precisely locate the rubber seal of an eyelid relative to the catcher.
This need is met by the improved eyelid positioning technique according to the present invention, wherein exact placement of an eyelid seal relative to a catcher pan is achieved by means of various flexures. With the technique of the present invention, an eyelid may be easily adjusted so that it properly diverts partially formed jets and blobs of ink into a catcher as the ink jet printer starts up.
In accordance with one aspect of the present invention, an eyelid positioning technique for an ink jet printer precisely positions the eyelid relative to the catcher to properly seal the print head.
Accordingly, it is an object of the present invention to provide an improved positioning means for orienting the eyelid relative to the printhead frame or catcher.
Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.